Feed containing a high content of marine unsaturated fatty acids has proven to be beneficial for the normal development and nutritional quality of many cultured aquatic species used in human consumption. Today, the cultivation of many marine fish and crustacean species largely depends on feeding of living prey during their first developmental stages.
Artificial diets such as micro diets are in general little successful in first feeding of the precocious marine fish and crustacean larvae. Several reason have been suggested which could cause the failure of micro diets in first feeding of marine larvae. Apart from reduced feeding rates due to a lower acceptance, an insufficient nutritional quality of the diet not covering the requirements of the larvae and/or the high organic load causing microbial problems and accompanied reduced water quality have been suggested as causative for the failure of artificial diets. Other suggested reasons are a reduced digestibility of the diets, which has been suggested to be a result of a possible lack of enzymes in the micro diets. The later reason is based on the fact that marine fish larvae lack a stomach in the larval phase and thus an efficient peptic digestion of feed. It has been suggested that the enzymes, as naturally included in the live feed prey, may be necessary for an efficient digestion of feed in the early stages or as a factor stimulating/activating the endogenous excretion and synthesis of larval digestive enzymes. Besides other factors, inadequate feeding during the first life stages of marine fish larvae such as the Atlantic cod, Atlantic halibut and turbot not only result in reduced growth, but also in high mortalities, decreased larval quality and mal pigmentations and mal developments.
In aquaculture, the most common prey organisms used to feed marine fish larvae are belonging to the group of rotifers especially some species belonging to the family of Brachionidae and to the brine shrimp Artemia spec. However, the nutritional composition of both, rotifers, and Artemia is naturally poor and not suitable for feeding of marine fish larvae. Therefore, these organisms have to be cultivated in intensive cultures and must be enriched with marine lipids, especially omega-3 fatty acids to improve their nutritional quality as prey organisms for marine fish larvae. This makes the cultivation of these prey organisms laborious and expensive. But in spite of the mentioned enrichment, both Artemia and rotifers are still not found nutritionally optimal for many larval species. This is reflected in mortality rates, growth rates, mal pigmentations and mal developments. Thus, there is a clear need for more optimal replacement diets for first feeding larvae as well as for early life stages of many cultivated crustaceans which e.g. use enriched Artemia as diet.
Furthermore, there is a large need for marine derived biological material rich in omega-3 fatty acids which is suitable for use in animal and human consumption. The increasing awareness of the beneficial effects of omega-3 fatty acids in sectors such as human consumption, pharmaceutical compositions and for health purposes in humans and other animals than fish further increases the quantitative demand for these fatty acids. Today, the main source for marine biological raw material are fish oil and fish meals. However, due to over-fishing accompanied by a globally increasing demand, there is an increasing need for new, unexploited biological marine sources to cover the demand.
Barnacles are an industrially hardly exploited organism. Barnacles are a type of arthropod belonging to the infraclass Cirripedia in the subphylum Crustacea. Barnacles are exclusively marine, and tend to live in shallow and tidal waters. They are sessile (non-motile) suspension feeders. Around 1,220 barnacle species are currently known. Two major types of barnacles are found in the oceans, the goose barnacles and the acorn barnacles.
Barnacles incubate their eggs in the body cavity, where they further develop to the one-eyed nauplius stage I. Nauplius I are released from the parent to the water column where they develop to nauplius stage II after a short time, typically within one day. Nauplius stage II have a fee-swimming, planktonic life lasting several weeks during which the nauplius II initiates an active feeding behavior. The free-living planktonic nauplius stages develop different appendages such as frontal horns which can already be observed in nauplius stage II. Several nauplii stages are then completed as plankton (nauplius larvae II to nauplius larvae VI), until converting into competent cyprid larvae. Cyprid is the final planktonic stage, which settles to a substrate, and thereafter undergoes a metamorphosis to the form of an adult specimen.
As barnacles attach themselves to man-made structures, especially to ships, as well as to biological material such as the shells of mussels for consumption, they are mainly and almost exclusively recognized as fouling organisms, their presence having negative economic consequences. Studies on barnacle so far have therefore mainly focused on factors influencing the attachment of barnacles as well as methods of elimination of barnacles from surfaces. Some mature barnacles are considered edible by humans, especially goose barnacles and giant barnacles. Goose barnacles are for example cultivated for this purpose.
Barnacles have been cultivated for commercial applications and research purposes with the aim to harvest them in their sessile stage. Lopez et al. 2012 describes the cultivation of spat barnacles to adult species for human consumption (López, D. A.; López B. A., Pham, C. K., Isidro, E. J. 2012. Potency of barnacle in aquaculture industry. In: Aquaculture, Editor: Muchlisin, Z., ISBN 978-953-307-374-5, Intech.).
Barnacles are also harvested from the wild by either collecting them in the planktonic stage or by removal of the sessile organisms.
Free-swimming planktonic barnacle larvae have been filtrated from the water and tested as a diet for juvenile lobster (Daniel, P. C., Bayer, R. C., Chapman, S. 1985. Barnacle larvae (Balanus spp.) as a potential diet for juvenile lobster (Homarus americanus). Aquaculture 46, p 67-70). Tests carried out with planktonic barnacles nauplii as live feed for fish larvae are also mentioned (see Wullur S., Sakakura, Y., Hagiwara, A. 2009. The minute monogonont rotifer Proales similis de Beauchamp: Culture and feeding to small mouth marine fish larvae. Aquaculture 293, p. 67), but they were not considered as optimal for this purpose.
Another application of barnacle raw material is described in CN1593464, which discloses an anti-inflammation and pain easing health product which is extracted from a barnacle raw material.
The objective technical problem to be solved by the present invention is to provide a new biological resource for nutritional products such as feed as well as methods for the exploitation of a new marine biological resource which can be industrially applied for different purposes. Thus, the present invention aims at providing a new biological resource for marine based products and a method for exploiting and producing it.
A further aim is to provide the new biological resource for the marine based product in a particular pure form without being mixed with other biological material.
In particular, the present invention has the objective to provide an optimized diet useful for feeding of aquatic animals such as fish and crustaceans, especially in their early life stages as well as for ornamental aquatic species.